The present invention relates generally to radio antenna equipment and is particularly directed to an antenna mounting device of the type which provides multiple mounting points for multiple individual antennas. The invention is specifically disclosed as an antenna mast adapter that provides an elongated crossarm that mounts to a standard mast, in which the crossarm exhibits mounting plates at its two opposite ends that are distal from the mast, and each mounting plate is capable of holding at least one individual antenna thereto.
Antenna mounting structures have been available for decades, including those that have multiple horizontal elements such as dipole elements mounted to a transverse horizontal boom, all as a unitary antenna structure. An example of this antenna structure is disclosed in U.S. Pat. No. 2,299,218 (by Fener), which discloses an adjustable dipole antenna unit that is mounted on a vertical pole. A transverse arm is mounted to the top of the vertical pole. Each end of the transverse arm has a dipole unit attached thereto, in which there are a pair of rods mounted horizontally, extending perpendicularly from each end of the transverse arm.
A similar structure is illustrated in U.S. Pat. No. 4,355,315 (by Zoulek), which discloses a log periodic directional antenna that provides a signal gain in one direction over a wide range of frequencies. The antenna mount is positioned vertically and supports a horizontal boom at its mid-point. The boom comprises two channel elements, that are disposed about a wooden core. A plurality of xe2x80x9clog periodic elementsxe2x80x9d make up the actual antenna elements, which are disposed from a shorter length at one end of the boom progressively to a longer length at the opposite end of the boom. These antenna elements are disposed on both sides of the boom. In one embodiment, the antenna elements are arranged horizontally extending from the boom, which provides for a horizontal polarization. In a second embodiment, the elements are disposed vertically, on both the top and the bottom of the boom, which provides for vertical polarization.
U.S. Pat. No. 4,005,432 (by Beccario) discloses a xe2x80x9ccommutated log periodic antenna arrayxe2x80x9d used for automatic direction finding. This antenna array uses a vertical support mast and a base plate that supports eight individual horizontal members that extend from the center of the base plate at 45 degree angles from one another. Each of these eight extending horizontal members has attached a plurality of xe2x80x9clog periodic antennasxe2x80x9d that extend vertically above and below each of the members. These antenna elements are of varying length, from the shortest element at the furthest point from the center of the support mast to the longest element that is closest to the center of the support mast.
U.S. Pat. No. 2,445,336 (by Rauch) discloses an antenna mounting apparatus that holds six xe2x80x9cradiatorsxe2x80x9d (which are antenna elements). A vertical mast holds a base plate, and this base plate provides support for a tapered head that provides three radiator sockets. The sockets hold xe2x80x9cfed radiators,xe2x80x9d which extend upward at an angle that is about 30 degrees from vertical. The base plate also provides three receptacles that contain radiator sockets for three xe2x80x9cgrounded radiatorsxe2x80x9d that extend downward at an angle about 30 degrees from vertical.
U.S. Pat. No. 3,560,987 (by Lockwood) discloses a support boom to which a planar antenna array is attached. A vertical mast at its top supports a horizontal frame. The horizontal frame then supports a longer horizontal main boom, which extends in parallel to the support frame, but extends at a longer horizontal distance. Multiple conventional antenna field elements are mounted to the main boom in a horizontal direction, much as would be seen with any outdoor T.V. antenna.
A patent disclosing mounting of whip antennas is U.S. Pat. No. 5,252,985 (by Christinsin), which discloses a whip-tilt adapter that allows a whip antenna to be mounted either vertically or near-horizontally. The adapter comprises a pivotable vertical pipe that has a vertical mounting point at the top of the vertical pipe. In addition, there is at least one near-horizontal pipe that joins with the vertical pipe. The near-horizontal pipe has a mounting port to which the whip antenna can be attached to position the whip antenna in a near-horizontal attitude. A second whip antenna can also be mounted to a second near-horizontal member, or it could instead be mounted to the top of the vertical shaft (i.e., in a vertical orientation).
U.S. Pat. No. 5,221,929 (by Ott) discloses an auxiliary antenna assembly that can be used for magnetically-attached antennas, such as those used for citizens band radios on automobiles. The antenna is to be connected to a support platform, and the support platform is hinged to the base unit that contains the magnetic mount. The hinge allows the antenna to yield to an obstruction without dislodging the complete antenna assembly from the vehicle.
None of the above designs provide a means for mounting multiple unitary antennas on a single mounting platform. Instead, each antenna is mounted to its own mast, or other similar mounting platform. It would be an improvement if several unitary antennas could be mounting onto a single mounting platform for ease of installation, especially in situations where different antennas of different frequency band characteristics could be mounting on a single platform.
Accordingly, it is a primary advantage of the present invention to provide an antenna mast adapter that, as a unitary structure, holds a plurality of individual antennas in place.
It is another advantage of the present invention to provide an antenna mast adapter that uses a crossarm to hold more than one antenna at opposite ends of the crossarm, and holds the individual antennas apart from one another and from the mast to which the antenna mast adapter is mounted.
It is yet another advantage of the present invention to provide an antenna mast adapter in which the crossarm includes mounting plates that each hold one or more individual antennas in place using mechanical and/or magnetic mounting means.
It is a further advantage of the present invention to provide an antenna mast adapter that can mount a pair of similar-type antennas to increase the transmission power or receiver sensitivity, while also holding other pairs or singleton antennas having different frequency band characteristics.
It is still a further advantage of the present invention to provide an antenna mast adapter that runs an individual waveguide for each of a plurality of individual or paired antennas that are mounted onto a crossarm of the antenna mast adapter.
It is yet a further advantage of the present invention to provide an antenna mast adapter in which the crossarm includes openings to reduce wind resistance.
Additional advantages and other novel features of the invention will be set forth in part in the description that follows and in part will become apparent to those skilled in the art upon examination of the following or may be learned with the practice of the invention.
To achieve the foregoing and other advantages, and in accordance with one aspect of the present invention, an improved antenna mounting device is provided in the form of an xe2x80x9cantenna mast adapterxe2x80x9d which is capable of holding several different antennas in place. In the embodiments illustrated herein, the antenna mast adapter is designed to mount onto a vertical mast, although other orientations could be used without departing from the principles of the present invention. One major element of the antenna mast adapter is a xe2x80x9ccrossarmxe2x80x9d that runs generally perpendicular to the mast. This crossarm provides at least two xe2x80x9cmounting platesxe2x80x9d to which individual antennas are mounted, either using mechanical mounting means or magnetic mounting means. The crossarm is generally designed to provide these mounting plates at the extreme ends of the crossarm, thereby providing an air gap between the antennas and the mast.
The crossarm can be constructed from different shaped materials, although its general shape consists of an elongated plate material or an L-shaped bracket (or angle bracket) that is held in place against the mast by nuts and bolts, preferably U-shaped bolts. In one preferred embodiment, the crossarm is fabricated from blank sheet material by first punching its outer perimeter, along with any desired openings, and then formed into an angle bracket shape by a press brake. In another preferred embodiment, the crossarm includes openings in the form of through-holes or cut-outs in the main elongated plate material, in which these openings reduce the wind resistance of the crossarm. This can aid in allowing the antenna mast adapter to be used in high winds, either on a stationary structure, or on a mobile device, such as a land vehicle.
In general, the antenna mast adapter provides mounting points for several different antennas, each of which is connected to an individual radio via a waveguide, such as a standard antenna cable. In such general applications, each antenna receives and/or transmits at a different frequency band than the other antennas mounted to the same antenna mast adapter.
In some more specialized applications, a pair of similar antennas could be mounted proximal to one another and their individual waveguides connected to a Y-adapter to combine their two waveguides into a single waveguide that is connected to a single radio device. The pair of similar antennas could be mounted co-linearly in the same vertical line, in which the top antenna mounts pointing in one direction, and the bottom antenna mounts pointing in the opposite direction. In such specialized applications, each antenna of the pair (of antennas) receives and/or transmits at the same frequency band, although at a different frequency band as compared to other antennas mounted to the same antenna mast adapter.
Still other advantages of the present invention will become apparent to those skilled in this art from the following description and drawings wherein there is described and shown a preferred embodiment of this invention in one of the best modes contemplated for carrying out the invention. As will be realized, the invention is capable of other different embodiments, and its several details are capable of modification in various, obvious aspects all without departing from the invention. Accordingly, the drawings and descriptions will be regarded as illustrative in nature and not as restrictive.